Microfluidic Approach for Rapid Discovery of Enzymes for Microplastic Breakdown and Environmental Impacts

Context It is predicted that 121 million tonnes of plastic waste will be produced per year by 2050. If practices and public policies do not change, this represents a massive challenge world wide both to manage its safe breakdown and removal from the environment. There is a move away from using fossil fuels as starting materials for plastic production and to move to biobased starting materials. Although this approach contributes to the sustainability of plastic production, the breakdown products still present a potential risk to animal and human health. This project seeks to accelerate our current knowledge regarding microplastic waste breakdown using ‘state of the art’ rapid evolution of biocatalysts to tackle a range of fossil derived synthetic and new bio-derived plastics and their breakdown products. In parallel we will also develop enzymes able to degrade environmentally sourced microplastic waste. This interdisciplinary approach directly addresses the current challenges these pollutants are causing within the environment and the ecotoxicology effects they have on marine and freshwater organisms. Challenge Our challenge is to speed up the optimisation of new sustainable enzymes that can address the breakdown of different microplastics. The new high-throughput assay and screening platform we will build will enable us to screen up to 10 million enzyme mutants per day dramatically increasing the current throughput. We will characterise the breakdown products using standard analytical techniques to understand exactly what chemicals are released into the environment. Although up and coming so called ‘biodegradable’ plastics such as polylactic acid and polybutylene succinate are gaining traction, their full breakdown requires specific conditions such as industrial composting facilities. Often they are not completely degraded and can also be of made up of mixed polymers to optimise specified performance. Most importantly recent research has shown that their breakdown into micro and nanoparticles is detrimental to living cells and whole organisms in their natural habitat. Aims and Objectives Our overall aims and objectives are to contribute to the worldwide problems associated with plastic waste using our inter-disciplinary team which offers complimentary expertise in biophysics, biochemistry, chemical synthesis and ecotoxicology. Bringing together our interdisciplinary team will allow a unique perspective to address this important problem of plastic waste management. More specifically, we will aim to improve currently known plastic-degrading enzymes towards complete breakdown of plastics, identify the breakdown products released and test whether they are harmful to model aquatic species. To accelerate enzyme discovery, we will develop a novel technology that allows us to rapidly test millions of different enzymes for the ability to degrade three different types of plastics, including bio-derived ones. Potential Applications The applications of the very rapid optimisation of new enzyme biocatalysts for plastic degradation will include improved waste management, accelerated environmental cleanup, rapid industrial composting and the design of new ‘safe-by-design’ biodegradable plastic materials with low ecotoxicity. In summary the important benefits from this work will be the development of ‘state of the art’ methods of microfluidic evolution of new sustainable enzymes for breakdown of a selection of different plastics. The knowledge gained in this project will help the management of microplastic accumulation in the environment and will provide a greater understanding of its overall toxicity to marine and freshwater organisms.